Clutch plate



Aug. 29, 1950 w. v. THELANDER CLUTCH PLATE Filed Feb. 17, 1943 PatentedAug. 29, 1950 *CLUTCH PLATE W. Vincent Thelander, Auburn, Ind., assignerto Dana Corporation, Toledo, Ohio, a corporation of Virginia ApplicationFebruary 17, 1943, Serial No. 476,133

2 Claims.

This invention relates to motion transmitting elements, and is moreparticularly concerned with improvements in friction clutch plates forautomotive use.

The principal object of my invention is to provide a clutch plate havingspring means between the relatively oscillatory inner and outer elementsof the plate for cushioning purposes and incorporating fluid dampingmeans in the hub to eliminate the tendency for the springs and otherportions of the hub structure to soundoff under certain conditions inthe operation of the clutch.

In two earlier copending applications, Serial No. 316,088, iled January29, 1940, and Serial No. 366,960, led November 25, 1940, which resultedin Patents 2,337,134 and 2,337,135, issued December 21, 1943, Idisclosed as part of the fluid damping means an interfitting piston andcylinder associated with each of a plurality of coiled compressionsprings forming the spring cushioning means, the piston and cylinderserving not only to form a Iluid pumping device using the fluid dampingmedium as its working iluid to give increased cushioning action in onedirection and in the other direction check the recoil of the springs soas to smoothen the drive, but also serving as a spring retainer so as toprevent rubbing contactbetween the spring and adjacent portions of theplate. An important objectof my present invention is to provide a pistonand cylinder of improved construction with a view to improving thehydraulic action and enabling quantity production of clutch plates ofthis kind, all adhering closely to a predetermined standard ofperformance.

A salient feature of the clutch plate of the present invention lies inthe provision of a relatively loose iltting piston in the workingcylinder, the piston being equipped with an enlarged rubber seal ring,which gives a substantially perfect seal while compensating by thedistortion thereof for whatever angularity the piston may assume in thebore of the cylinder, so that there is definite freedom from any dangerof the parts seizing or binding and the parts yneed not be manufacturedto such close tolerances, improved hydraulic action being obtainedbecause of the fact that there is substantially no leakage past thepiston with such a construction and negligible fric-tional resistance tomovement, substantially the entire resistance to movement being thatoccasioned by the flow of the working iiuid through a port ofpredetermined size provided in the wall of the cylinder.

The invention is illustrated in the accompanying drawing, in which- Fig.1 is a rear view of a clutch plate embodying my invention, showingapproximately half of the hub housing plate broken away so as to betterillustrate the hub construction, and

Fig. 2 is a sectional view of one of the piston and cylinder assembliesof Fig. l, on an enlarged scale, showing the same in connection with theassociated coiled compression spring.

The same reference numerals are applied to corresponding parts in thesetwo views.

Referring to the drawing, the clutch plate shown comprises relativelyrotatable inner and outer portions, the inner portion being formed by acenter hub I0 splined for driving connection with the driving shaft ofan automotive transmission and provided with an annular flange II ontoopposite sides of which two circular sheet metal plates I2 are riveted,as indicated at I3. These plates have a plurality of equallycircumferentially spaced openings I4 provided therein, four in thepresent instance, one for each of a plurality of spring cushioning meansI5, the openings in the two plates being in register with one another.Assembled in each opening I4 with the spring I5 is a piston IB andcylinder I'I extending into the spring from opposite ends and providedwith enlarged circular head ends I8, larger in diameter than the springso as to space the ends of the spring from adjacent portions of theplate and avoid wear on the end coils. Inasmuch as the present inventionis primarily concerned with improvements in the piston I6 and cylinderI1, those parts will be described in greater detail hereinafter. A ringI9, the inner and outer peripheries 20 and 2l of which are in concentricrelation with the periphery 22 of the ange II, has notches 23 cuttherein in register with the openings I4 and is disposed between theplates I2 for engagement of .the ends of the notched portions 23 withthe spring cushioning means, the drive being taken at one end of thenotched portions 23 and by the respectively opposite ends of theopenings I4, in a manner well understood in this art. The radially outersides 24 of each of the notches 23 in the ring I9 are struc'k on arcsconcentric with the inner and outer peripheries 20 and 2|, and the headends I8 of the pistons I6 and cylinders Il are tapered, as indicated, toconform to these arcs 24. The ring I 9 is riveted at circumferentiallyspaced points, as indicated at 25, between the peripheral ilanges 26 oftwo sheet metal housing plates 21. The latter have central circularopenings 28 through which the end portions of the hub III project. Theplates 21 define therebetween an annular oil or grease chamber 29 lledwith a heavy lubricating oil or grease, a small portion of which isindicated at 30. Gaskets, preferably of an oil resistant rubber, such asneoprene, are preferably provided between the outer marginal portions ofthe plates 21 and around the inner marginal portions thereof, asdisclosed in the copending application Serial No. 366,960, to seal thechamber 29 against leakage of the oil or grease 30. Stampings 3 I, asalso disclosed in said copending application, are riveted with thehousing plates 21 to the ring I9 by the rivets 25 and have the annularfacing rings 32 secured thereon, as indicated at 33.

In operation, when relative movement takes place between the inner andouter portions of the clutch plate, the springs I5 are compressed tocushion the drive. At the same time the heavy oil or grease 30 withwhich the cylinders I1 are filled is discharged to some extent throughbleeder holes 34, so that these pumping devices add materially to thecushioning effect, accordingly relieving the springs I5 of some of theload. The recoil action of the springs I5 is also checked by the pistonsand cylinders I6-I1, because their return to normal extendedrelationship is retarded as a result of the restriction of the bleederholes 34 through which the heavy oil or grease must flow. In that waythe secondary vibrations are absorbed and a smooth drive is obtained. Incontrast to clutch plates employing friction braking means to resist thereturn of the parts to normal relationship after compression of thesprings, the present piston and cylinder construction with the heavygrease or oil 30 affords the desired checking action without perceptiblewear on the relatively movable piston and cylinder parts inasmuch as theoil or grease serves to lubricate these parts. In addition, the oil orgrease 30 serves for dampening or sound deadening. The oil or greaseabsorbs the primary vibrations substantially entirely, and working withthe pistons and cylinders serves to substantially completely dampensecondary vibrations. The springs I5 cannot sound-01T due to vibration,because they are immersed in the heavy oil or grease, and this heavy oilor grease has the same sound deadening effect upon all of the otherparts with which it is in contact.

In accordance with the present invention,- the piston I 6 is madesufficiently undersize to t fairly loosely in the cylinder I1, that isto say, with more than the ordinary working clearance, and has anannular groove 35 provided therein in which is seated a ring 36 ofneoprene-a synthetic rubber which is impervious to oil. The seal ring 36has an inside diameter large enough to permit slipping the ring over theend of the piston and into the groove without too much stretching and,on the other hand, small enough to insure a certain amount of pressureof the ring circumferentially on the bottom of the ,groove 35 when thering is in place. The outside diameter of the seal ring is large enoughin relation to the inside diameter of the bore 31 of the cylinder I1, asindicated in dotted lines in Fig. 2, to insure a tight sealing fit inthe bore when the ring is forced into the bore and thereby compressed tothe barrel-shaped section shown in full lines in Fig. 2. The outer endof the bore 31 is ared slightly, as indicated at 38, to facilitatecompression of the seal ring I6 radially to the extent necessary inentering the same into the bore. It should be apparent that when thepiston with the seal ring thereon is entered in the bore an improvedhydraulic action is obtained, because the seal ring 36 conforms to thebore 31 in any and all positions of the piston regardless of whatevervariation in shape or size there may be at one or more points. As aresult, plates made in accordance with my invention may be manufacturedin large quantities with reasonably good assurance of all of the platesadhering closely to a given standard of performance, and such goodperformance is furthermore assured for a much longer period of service,inasmuch as the size of the bleeder hole 34 is really the onlycontrolling factor in the operation of the piston and cylinder assembly,instead o being only one of several factors where a plain piston isemployed, it being, of course, understood that the bleeder holes 3l maybe reduced or increased in size in the application of clutch plates ofthe present invention to different makes and sizes of cars. The pistonis kept substantially centered and therefore evenly spacedcircumferentially with respect to the surrounding wall of the cylinder,and in that way frictional resistance to movement is reduced to aminimum and there is no appreciable wear on the piston I6 and cylinderI1, whereas if the assembly depended upon a close working t of thepiston in the cylinder to prevent leakage around the piston, the wearwould soon make itself apparent in the poorer hydraulic action obtainedand there would be meanwhile too much resistance to relative movementand also too much danger of the piston seizing or binding, especially ifthe piston expanded enough with change of temperature. The rubber sealring gives a universal joint action in so far as accommodating itself towhatever angularity the piston might assume in the bore is concerned,and it gives the same substantially perfect sealing action regardless ofwhatever slight inclination the piston may assume in the bore. The sidewalls of the groove 35 diverge outwardly, as indicated at 39, so thatthe seal ring 36 can be compressed radially to barrelshaped section tothe extent indicated without being jammed into tight contact with theside walls of the groove and being thereby restrained so far as itsfreedom of action is concerned, this construction also allowing greaterfreedom and flexibility of operation of the piston in the cylinder.

It is believed the foregoing description conveys a goed understanding ofthe objects and advantages of my invention. The appended claims havebeen drawn to cover all legitimate modifications and adaptations.

I claim:

1, A liquid shock absnrber unit for a friction clutch of the typeincluding relatively osciilatable members between which the shockabsorber unit is mounted for transmitting driving force from one of saidmembers to the other, said unit comprising a cylinder open at one endand having a head portion on the other end for abutting one of theoscillatable clutch members, an undersize piston having a loose t andbeing capable of limited rocking motion in the cylinder, said pistonincluding a head portion outside the cylinder for abutting the otheroscillatable clutch member, said piston having an annular groove and aresilient rubber sealing ring seated in the bottom of said groove underradial compression between the same and the 'walls of the cylinder tohave sealing engagement therewith, the width of the outer portion of theannular groove being greater than that of the rubber sealing ring, theloose fit of the piston in the cylinder being such as to permit limitedrocking action of the piston in the cylinder about said resilient rubbersealing ring, whereby to eliminate any tendency of said piston to bindin the cylinder upon application of force on said cylinder and pistonalong lines extending at' an angle to the axis thereof upon relativeoscillating motion of said clutch members, and said cylinder having ableeder hole therein for the inlet and outlet of liquid in thereciprocation of the piston.

2. In a liquid dampened clutch plate comprising relativelyoscillatablelinner and outer members, a coiled compression spring forresisting relative rotary movement between the inner and outer members,an interfltting piston and open ended cylinder associated with saidspring and normally held in extended relation to one another by thespring, the cylinder extending axially into the spring from one end andthe piston extending axially into the spring from the other end, thepiston and cylinder each having an en- -.i

larged substantially circular head portion on the outer end thereof forabutment on the inner side thereof with the adjacent ends of the spring,respectively, and transmitting pressure to the spring to compress thesame in the relative rotary movement between the inner and outermembers, the improvement which consists in that the piston is undersizewith respect to the bore of the cylinder andhas a loose t and beingcapable of limited rocking motion therein, said piston having an annulargroove and a resilient rubber sealing ring seated in the bottom of saidgroove under radial compression between the same and the cylinder wall'to center the piston in the cylinder and seal the passage between thesame, the width of the outer portion of the annular groove being greaterthan that of the rubber sealing ring, and the loose lit of the pistoninthe cylinder permitting limited rocking motion of the piston in thecylinder with said rubber sealing ring as a fulcxum whereby to eliminateany tendency of said piston to bind in the cylinder upon relativeoscillatory motion of said inner and outer members with resultantapplication of pressure on the cylinder and piston along lines at anangle to the axis thereof, and means affordingv restricted inlet andoutlet of uid to and from said cylinder upon relative reciprocation ofthe piston and cylinder.

W. VINCENT THELANDER.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 454,360 Keene June 16, 1891879,058 Little Feb. 1l, 1908 926,620 Sundh June 29, 1909 959,170 Rileyet al. May 24, 1910 1,423,904 Blyburg July 25, 1922 1,608,877 ElliottNov. 30, 1926 2,115,383 Christensen Apr. 26, 1938 2,227,838 Main Jan. 7,1941 2,256,868 Perkins Sept. 23, 1941 2,259,422 Karlberg Oct. 14, 19412,316,820 Thelander Apr. 20, 1943 2,360,731 Smith Oct. 17, 1944

